The photo is sourced from cyrillitsa.ru
From the standpoint of physics, hydrates are water molecules, which under high pressure and low temperature turn into carcasses carrying gas molecules inside. One volume of hydrates may “contain” 160 volumes of gas, which may be recovered by simple warming, and the water received after melting may be re-used. “The main drawback of the hydrate technology impeding its broad implementation is low speed of hydrates generation and growth. The so-called promoting agents are used to resolve this problem; they are capable of facilitating the process of hydrates formation – for example, chemical agents-promoters, nano particles, porous media”, KFU is citing Mikhail Varfolomeev, the Head of the Chair of the Geology and Oil-and-Gas Technologies Institute of KFU.
The most well-known commercial agent is sodium dodecyl sulphate – sodium salt of lauryl sulphuric acid, which is commonly used in industry a strong cleaning and wetting agent. The KFU scientists in the course of their experiment compared the impact of sodium dodecyl sulfate additives and sulphated castor oil have on formation of methane hydrates and methane-propane gas mix in porous medium (silica sand in this case).
“We demonstrated that in the case of methane hydrate after adding the promoters into the system in concentration of 0.5%, the volume of hydrate increases with the increase of the ratio between the sand mass to the solution, which is different from the system based on pure water. It is quite possible, that is because the promoters increase the formation of hydrates on the reactor walls”, увеличивают рост гидратов на стенках реактора», KFU is citing Julia Chirkova, the junior research fellow of the Geology and Oil-and-Gas Technologies Institute. “This effect is not observed for gas mix hydrates, which shows the differences in promoting hydrate with sI structure (methane hydrate) and sII structure (natural gas hydrate). The kinetic calculations based on JMA equation showed that both agents (sulphated castor oil and sodium dodecyl sulphate) increase the speed of hydrates formation, but the agent created in KFU allows to do that in milder conditions”.
The research also showed that castor oil increases its effect when used in a porous medium. When just castor oil is used, the gas-to-hydrate conversion ratio is 70%, but using it in combination with sand gives 95% conversion ratio.
Scaling-up and commercialising the new technology will allow for faster and easier development of minor and mid-size fields, where using traditional methods of storage and transportation is too capital-intensive. “At the same time, gas hydrates will allow for decreasing the volumes of the flared associated petroleum gas at the fields and for gasification of minor villages. Low temperatures common in the Russian North is this case represent an advantage for implementing this technology”, KFU is citing Mikhail Varfolomeev.